Traffic signaling system



Sept. 10, 1940.

4 Sheets-Sheet 1 Filed 001:. 31, 1938 x g; S g g q a K) 3 IQ Q 0 NJJ Q QQ \Q INVENTOR. Elarence E. Lumax WM,MM

' ATTORNEYS.

Sept. 10, 1940. c. E. LOMAX TRAFFIC SIGNALING SYSTEM 4 Sheets-Sheet 2Filed 091;. 31, 1938 ATTORNEYS Sept. 10, 1940.

C. E. LOMAX TRAFFIC SIGNALING SYSTEM Filed Oct. 31, 1938 4 Sheets-Sheet3 Clarence ELumax W,M.MM

ATTORNEY5.

p 10, 1940- c. E. LOMAX 2,214,253

TRAFFIC SIGNALING SYSTEM Filed Oct. 31, 1938 4 Sheets-sheaf 4[Memes/7017 /Va 4 frzfensec/Yon /V0. 4

[Mensa/7072 /V0. 4

[Man e/700 /V0. 2

, INVENTOR. Clarence E. Lnmax BYM,M7MM

A TTORN E Y5.

Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE v AssociatedElectric Laboratories,

Inc., Chicago, Ill, a corporation of Delaware Application October 31,1938, Serial No. 237,897

15 Claims.

5 intersections along a highway or street are controlled from a masterunit over a line interconnecting the master unit and signal controlunits located at the respective traffic intersections.

In signaling systems of the character noted, the plurality of signalslocated at each traific intersection conventionally comprise a pluralityof groups of lamps, each group including red, green and amber signallamps positioned to face in one traffic approach direction, thereby togive stop, right-of-way and caution indications to approaching motorvehicle operators or pedestrians. In a four-way intersection, four suchgroups of lamps are usually provided for respectively signaling in eachof the four trafiic approach directions. The lamps at each intersectionare arranged automatically to be controlled by the apparatus embodied inan associated control unit, which apparatus functions to energize thelamps in a definite cyclic order. Thus, on a north-south, east-westintersection, the north-south right-ofway signals are energized for aportion of each operating cycle simultaneously with the east-west stopsignals. During another portion of each operating cycle, the north-southstop signals are energized simultaneously with the east-westright-of-way signals. The respective portions of each operating cycleallotted to trafiic right of way to the respective intersecting trafiiclanes include periods conventionally known as changeover intervalsduring which the caution or amber signals are alone energized or areenergized in conjunction with right-of-way or stop signals. A completeoperating cycle of the group of lamps at any intersection includes,therefore, the two periods respectively giving right of way to the twointersecting traffic lanes, which periods are partially overlapped bythe respective change-over periods. Usually the operating cycles of thesignaling devices located at the various intersections of a main orarterial highway are related in a particular manner, designed to providethe most expeditious movement of heavy traffic along the main highway.One method of controlling heavy trafific proceeding along a highway ofthis character is the well-known progressive type of control. With thisform of control, the operating cycles of the signals at succeedingintersections are displaced predetermined increments in phase so thatthe right-of-way signals governing the traflic proceeding in thedirection of heavy trafiic density are successively energized, thuseffective-- ly providing right-of-way traflic indications which travelin the direction of travel of the heavy traflic. With this type ofcontrol, continuous movement of the heavy traffic is insured if thetraffic maintains an average speed which is above a predeterminedminimum. Probably thetwo-phase form of progressive control is the mostfavorable type of progressive control, as regards the trafiic proceedingalong the main or arterial highwayin both directions. In systemsutilizing tworphase progressive control, the trafilc rightof-way signalsat alternate intersections for gov-' erning traffic along the mainhighway are operated concurrently with the main highway stop sig-, nalsat the intervening intersections and vice versa. The advantage of thismode of control lies in the fact that trafrlc movement in one directionalong the main highway is not favored to the detriment of trafiic movingin the opposite direction along the main highway.

It is an object of the present invention to provide a tramc signalingsystem of the character described which operates on a two-phaseprogressive basis and is arranged in an improved manner such that greatflexibility is achieved with respect to the speed of the trafiicproceeding between predetermined ones of the controlled intersectionsalong the main highway or the highway having heavy traffic densitywithout materially impeding the movement of traflic along theintersecting highways. i

It is a further and more specific object of the invention to provide atrafiic control system of the character described which is arranged inan improved manner such that the percentage of each signaling cycle,during which the main highway ri'ght-of-way trafiic signals at certainintersections are operated, may be changed from a central control pointwithout affecting the operation of the main highway signals provided atthe other intersections.

It is another object of the invention to provide an improved trafiiccontrol system of the character described which is of simple andeconomical arrangement and operates in an improved manner to providereliable service at all times.

The invention is illustrated in its embodiment in a system forgoverning, on a two-phase progressive basis, main and cross trafiicproceeding along and across a highway having a plurality of trafiicintersections thereon. Apparatus comprising the usual master unit andcontrol units individually, located at the various intersections isprovided for controlling the operation of the In accordance with onefeature of the present invenation, the operation of this apparatus issuch that each signal cycle is divided into three portions. To this endthe indicated apparatus includes means for operating the main highwayright-of-way signals at certain of the intersections and the mainhighway stop signals at others of the intersections concurrently for oneportion of each signaling cycle; means for operating the main highwaystop signals at the first-mentioned intersections and the main highwayright-of-way signals at the other intersections for a second portion ofeach signaling cycle; and means for operating the main highwayright-of-way signals at all of the intersections for the third portionof each signaling cycle. More particularly, the arrangement is such thatthe main highway right-of-way signals at alternate intersections areoperated concurrently with the main highway stop signals at theintervening intersections for one portion of each signaling cycle andthe main highway stop signals at the alternate intersections areoperated concurrently with the main highway right-of-way signals at theintervening intersections for the second portion of each signalingcycle, whereas, the main highway right-ofway signals at all of theintersections are operated concurrently for the third portion of eachsignaling cycle. Through this arrangement the flexibility of the system,with respect to the speed of the trafic moving between alternateintersections, is materially enhanced. The above-mentioned apparatusalso includes means for operating the main highway caution signal ateach intersection concurrently with the associated rightof way signalfor an interval during the last part of the period during which theassociated rightof-way signal is operated. In accordance with a furtherfeature of the invention, additional control means are embodied in thecontrol apparatus for eliminating the above-described third portion ofeach signaling cycle and for extending one of the first and secondportions of each signaling cycle to include the time interval of thethird portion of the corresponding cycle. The provision of thislast-mentioned apparatus permits the system selectively to beconditioned to favor traflic proceeding along the main highway ortraffic proceeding along the intersecting highways.

Further features of the invention pertain to the particular arrangementof the apparatus whereby the above and additional operating features areattained.

The novel features believed to be characteristic of the invention areset forth with particularity in the appended claims. The invention, bothas to its organization and method of operation, together with furtherobjects and advantages thereof, will best be understood by reference tothe specification taken in connection with the accompanying drawings inwhich Figures 1, 2 and 3 illustrate a traflic signaling system havingembodied therein the features of the invention as briefly outlinedabove, and Fig. 4 is a series of graphs illustrating the mode ofoperation of the system.

Referring now more particularly to Figs. 1, 2 and 8 of the drawings, thesystem there illustrated comprises a plurality of control units l0,Illa, Iiib and we, a master unit [3 and a multiconductor line circuit 55comprising conductors I6, ll, l8, l9 and i9 interconnecting the masterunit with each of the control units. It will be understoodthatadditional control units controlsignals located at the respectiveintersections.

lable over the line circuit l from the master unit l3 may be provided ifrequired. As shown, the control unit it is arranged to control thesignals located at a traffic intersection l between an eastwest main orarterial highway 20 and a northsouth intersecting highway 2!. Similarly,the control unit 08. is arranged to control the operation of the signalslocated at a second traffic intersection 2 along the highway 20, thissecond traffic intersection being formed by the inte; section of anorthsouth street 2 la with the main highway 20. The third control unit101) is likewisearranged to control the signals provided at a trafficintersection 3 formed by the intersection of a third north-south street2|b with the main highway 28. Finally, the fourth control unit We isarranged to control the signals provided at a traffic intersection 4formed by the intersection of a fourth north-south street 2'0 with themain highway 20. The signals provided at the intersection l comprise agreen or right-of-way signal lamp 22, a red or stop signal lamp 23, andan amber or caution signal lamp 23 arranged to give indications to thetraflic traveling east and west along the highway 20. Also included inthe plurality of signals at the intersection l are the green, red andamber lamps 25, 2B and 2?, respectively, which are arranged to governtraffic traveling in the north and south directions along theintersecting highway 2|. These signaling devices have operating circuitstraced hereinafter, which commonly include bus conductors 28 and 29extending to opposite terminals of any suitable source of commercialfrequency current.

For the purpose of energizing the enumerated signals lamps provided atthe intersection l in accordance with control voltages impressed uponthe conductors of the line circuit 15, there are provided in the controlunit In three polarized relays indicated at 30, 40 and 50, respectively.The relay Bil, which is provided for the purpose of controlling theenergization of the lamps 22, 23, 25 and 26, includes a windingconnected between the conductors l6 and I8 of the line circuit I5, sothat it is operated between its two operating positions in response tovoltage of a predetermined polarity impressed between the enumeratedline conductors. The windings of the two polarized relays 4B and 50 areconnected in series across the conductors IE and IQ of the line circuitl5 and are so poled that the relay 40 assumes its operated position onlywhen voltage of one polarity is impressed across the indicated lineconductors, whereas the relay 5!] assumes its operated position onlywhen voltage of the reverse polarity is impressed across the twoenumerated line conductors. The relay 50 is provided for the purpose ofcontrolling the amber signal lamps 24 and 21 during the normal operationof the system. The relay 40, on the other hand, is provided for thepurpose of extinguishing any operated ones of the red and green signallamps provided at the intersection 2|, and of causing the continuousenergization of the amber or caution lamps 24 and 21 when the normaloperation of the system is discontinued. The relay 30 embodied in thecontrol unit I0 is preferably of the permanent magnet polarized type.More particularly, this relay is so constructed and arranged that, whenoperated to one position in response to energization of its windings bycur. rent. of one polarity, it remains in the operated position untilits windings are subsequently energized by current of the oppositepolarity, at which time it operates to the other of its two operatingpositions. Several different embodiments of this type of polarized relayare commercially available. The relays 4B and 50, embodied in thecontrol unit II], are preferably of the conventional permanent magnetpolarized type, such that each thereof assumes its operated positiononly when energized by current of a particular polarity and restoreswhen deenergized.

The control units provided at each of the intersections 2, 3 and i andat each of the other intersections associated with the line circuit I5are, in all respects, identical with that provided at the intersection Iand described in the preceding paragraph. Accordingly, the elementsprovided at the intersections 2, 3 and 4 which correspond to theelements provided at the intersection I have been indicated by the samereference numerals distinguished only by the addition of the subscriptsa, b and c, respectively. The relays 38, 30b, etc., respectivelyembodied in the control units located at the odd numbered intersections,are all connected across the same pair of conductors of the line circuiti5, namely, the conductors I6 and !8. The relays 30a, 300, etc.,

which are respectively embodied in the control units located at the evennumbered intersections, on the other hand, are connected to be energizedover a difierent pair of conductors of the line circuit I5. Moreparticularly and considering the control unit Iil'a by way of example,it will be noted that the winding of the polarized relay 30a isconnected to be energized by control voltage of a predetermined polarityimpressed across the conductors I6 and I9 of the line circuit I5.

Referring now more particularly to the details of the master unit I3,this unit comprises a cyclically operating rotary stepping switch Iii!which is arranged to be operated in accordance with the pulses generatedby a pulse generator BI. The rotary switch 68 may be of any standardcommercial construction and comprises four sets of bank contacts 62, 63,64 and 64' of twentyfour points each, wipers E5, 66, 61 and 67',respectively associated with the contact sets; I52, I53, E i and 5d, andmeans comprising a motor magnet 58 and a ratchet and pawl mechanism, notshown, for driving the enumerated wipers over the contacts of theirrespective associated contact sets. The pulse generator 6 I is arrangedto generate spaced control pulses at two different rates. Thisgenerator, which is only diagrammatically shown, may, if desired, takethe form of a circuit breaker driven by a synchronous motor through aspeed reducing gear mechanism and arranged intermittently to applyground potential to the two conductors 69 and I0. In the arrangementillustrated it is contemplated that the slow pulses shall be applied tothe conductor 69 and the fast pulses to the conductor 10. These pulsescontrol the energization of the motor magnet 68 embodied in the rotaryswitch BI]. The switch 66, in turn, functions to control the applicationof control voltage to the various conductors of the line circuit I5.More particularly, a relay I5, arranged to be controlled by the switch60, is provided for impressing the voltage of a current source I8 acrossthe conductors I6 and I9 of the line circuit I5, and a second relay Bil,also controlled by the switch 60, is provided for impressing the voltageof a second current source 83 across the indicated line circuitconductors. The two current sources l8 and 83 are so poled that, whenthe relay I5 operates, voltage of one polarity is impressed across theconductors I6 and I9, and, when the relay operates, voltage of theopposite polarity is impressed across the indicated line conductors. Apair of additional relays 85 and 90, also under the control of therotary switch 65, are provided for controlling the application ofvoltage to the conductors I6 and E8 of the line circuit I5. Thus, therelay 85 is arranged to impress the voltage of the source I8 across theconductors I5 and I8, whereas the relay 96 is arranged to impress thevoltage of the current source 83 across the two indicated conductors.Control of the caution or amber signals located at the respectiveintersections is achieved through the provision of two additional relaysand 93, the first of which is operative under the control of the switch65 to impress the voltage of the current source 83 across the conductorsI6 and i9 of the line circuit l5 for predetermined intervals during eachsignaling cycle, and the second of which is operative under the controlof the switch 58 to impress the voltage of the source 83 across theconductors I6 and ll of the line circuit I5 for predetermined intervalsduring each signaling cycle. The master unit I3 further comprises threekey controlled manually operable switches indicated at 91, 98 and 99,respectively, The switch 9i is provided for the purpose of selectivelyenergizing the operating magnet 58 of the rotary switch 60 in accordancewith the ground pulses of diiierent rates impressed upon the twoconductors 69 and III by the pulse generator SI, thereby to change the,

time interval of a complete signaling cycle. The switch 98 is providedfor the purpose of arresting the operation of the switch 65, causing thedeenergization of all of the red and green signal lamps provided at theintersections controlled over the line circuit I5, and causing thecontinuous illumination of the amber signal lamps located at all of theintersections. Finally, the manually operable switch 99 is embodied inthe master unit l3 for the purpose of changing the percentage of red togreen displays at certain of the intersections controlled over the linecircuit I5.

Current for energizing the operating magnet 68 of the rotary switch 58and the relays I5, 8!], 85, ea, 93 and 95 is derived from the currentsource 83. In practice, the terminals of this source are connected totwo bus conductors which are commonly included in the operating circuitfor the magnet 68 and the respective operating circuits for the variousenumerated relays. For convenience in describing the circuits, however,the source 83 has been individually indicated in each circuit.

Referring now more particularly to the operation of the apparatus, theground pulses applied to the conductor 69 are efiective to cause theintermittent energization of the rotary switch operating magnet 68 overa. circuit extending by way of the conductor 69, the switch springs not,58!, ml and H36, and the winding of the magnet 58 to the negativeterminal of the current source 83. Each time this magnet is energizedover the circuit just traced it operates in conjunction with itsassociated ratchet and pawl mechanism to advance the wipers I55, 56, 61and El" one step. With the wipers 65 and 56 standing in the positionsillustrated, such that they engage their respective associated firstcontacts, the two relays I5 and 8'5 are both energized. Specifically,the operating circuit for the relay I5 extends by way of the groundedwiper 65, the multipled first to twelfth contacts of the set 62, thearmature 8|, and the winding of the relay I5 to the negative terminal ofthe current source 83. With the relay l5 energized over this circuit,the operating circuit for the relay 80 is held open at the armature i8and the voltage of the current source 18 is impressed across the lineconductors l6 and i9 over a path including the armature H.

The above-mentioned operating circuit for the relay may be traced asextending by way of the grounded wiper t6, the multipled contactsnumbered from one to twelve of the contact set 63, the armature 9! andthe winding of the relay B5 to the negative terminal of the currentsource 83. With the relay 85 energized, the operating circuit for therelay 9% is held interrupted at the armature 8t and the voltage of thecurrent source 18 is impressed across the line conductors l6 and I8 overa path including the armature 81.

With the relays l5 and 85 operated, such that the voltage of the source78 is impressed across the pair of conductors I5 and I9 and also acrossthe pair of conductors l6 and E3, the relays 33, 30a, 38b, 30crespectively embodied in the control units w, 9a, Hit and We, and theother corresponding relays embodied in the other units controlled overthe line circuit l5 are all energized. With the relay 36 energized bycurrent derived from the source '58, the green signal lamp 22 for givinga right-of-way indication to trafiic proceeding along the highway 20 andthe red signal lamp 2% for giving a stop indication to traliicproceeding along the highway 2! are energized. The circuit forenergizing the two lamps 22 and 26 may be traced as extending from oneterminal of the alternating current source by way of the conductor 29,the armature 43, the contact 45, the armature 34, the contact 35, thetwo lamps 22 and 26 in parallel, and the conductor 28 to the oppositeterminal of the current source. When the relay 3% embodied in thecontrol unit I01, provided at the intersection 3 is energized by currentderived from the source T8, the green signal lamp 22b for giving aright-of-way indication to traffic proceeding along the highway 20, andthe red signal lamp 2% for giving a stop indication to trafiicproceeding along the highway 2h, are energized, the circuit forenergizing these two lamps being exactly similar to that just tracedwith reference to the signal lamps 2 and Zii located at the intersectioni. In a similar manner, the green signal lamps respectively provided atthe other odd numbered intersections for giving right of way indicationsto tramc on the main highway 20 and the red signal lamps for giving stopindications to the cross highway trafilc are all energized when thecurrent source '58 is connected across the conductors i6 and is of theline circuit 15. When the relay 3% embodied in the control unit I 8aprovided at the intersection 2 is energized by current derived from thesource 18, the green signal lamp 25a for giving a right-of-wayindication to traffic proceeding along the highway Us and the red signallamp 253, for giving a stop indication to traffic proceeding along thehighway 29 are energized over a circuit which may be traced as extendingfrom one terminal of the alternating current source by way of theconductor 29s., the armature 43a, the contact 4521, the armature 34a,the contact 35a, the two lamps 23a. and 25a in parallel, and theconductor 28a to the opposite terminal of the current source. When therelay 33c embodied in the control unit Ills provided at the intersection4 is energized by current derived from the source '58, the green signallampific for giving a right-of-way indication to traffic proceedingalong the highway 216 and the red signal lamp for giving a stopindication to traihc proceeding along the highway 2!] are energized overa circuit which is exactly similar to that traced above with referenceto the lamps 23a and 25a located at the intersection 2. In a similarmanner, the green signals respectively provided at the other evennumbered intersections for giving right-of-way indications to the crosshighway traffic and the red signal lamps at the same intersections forgiving stop indications to traffic proceeding along the main highway 2llare all energized when the current source i8 is connected across theconductors l6 and ill of the line circuit l5. With the manually operableswitch 99 in its normal position, the contacts numbered from I to l2 ineach of the two contact sets 62 and 63 are multiplied together and therelays 15 and 85 are concurrently energized during the same period ofeach operating cycle of the switch 68. Hence, the right-of-way signalsprovided at the odd numbered intersections along the highway 20 areenergized or operated concurrently with the main highway stop signalsrespectively provided at the intervening or even numbered intersectionswhile the wipers of the switch 65! are traversing their respectiveassociated first twelve contacts.

During the movement of the switch wipers 65, 63, 67 and 6'! over thefirst ten contacts of their respective associated contact sets, theamber or caution signals located at the various intersections aredeenergized. When, however, the wipers 57 and 67' are operated intoengagement with their associated eleventh contacts, circuits arecompleted for energizing the relays 9.3 and of the master unit l3,whereby these relays are caused to operate to cause the energization ofthe cross highway amber signal lamps at the even numbered intersectionsand the main highway amber signal lamps at the odd numberedintersections. The circuit for energizing the relay 95 extends by way ofthe grounded wiper El, the multipled eleventh and twelfth contacts ofthe set 66, and the winding of the relay 95 to the negative terminal ofthe current source 83, and the circuit for energizing the relay 93extends by way of the grounded wiper 67, the multipled eleventh andtwelfth contacts of the set 64 and the winding of the relay 93 to thenegative terminal of the current source 83. Upon operating, the relay 95completes apath including the armature 96 and the two switch springs I03and N34 for impressing the voltage of the source 83 across theconductors l6 and N3 of the line circuit 15. The relay 93 similarlycompletes a path including the armature 9d and the switch springs H4 andM5 for impressing the voltage of the source 83 across the line circuitconductors l6 and H. The polarity of the voltage impressed across thetwo pairs of conductors l6, l9 and I ii, i 7 is such that the relays 50,50a, 58b and 5% embodied in the control units Ill, Ella, its, and lo,respectively, and the other corresponding relays individually embodiedin the other control units associated with the line circuit I5 are allcaused to operate. The relays fill, 48a, 40b, 68c, etc., respectivelyconnected in series with the relays 50, 59a, 58b, 50c, etc., are sopoled that they do not operate when the current source 83 is connectedacross the indicated two pairs of line conductors. Upon operating, therelay 59 completes a circuit for energizing the amber lamp 2%, therebyto cause this lamp to display a caution signal to traffic proceedingalong the highway 20. The circuit for energizing the lamp 24 may betraced as extending from one terminal of the alternating current sourceby way of the conductor 29, the armature 5!, the contact 52, thearmature 3|, the contact 32, the lamp 24, and the conductor 28 to theopposite terminal of the current source. The relay 50h embodied in thecontrol unit lab provided at the intersection 3, upon operating,completes a circuit for energizing the amber lamp 24b, this circuitbeing exactly similar to that just traced with reference to the amberlamp 24 provided at the intersection l. In a similar manner, the ambersignal lamps corresponding to the lamp 24 and provided at the other oddnumbered intersections are also energized in response to theabove-described operation of the relay 93 to impress the voltage of thesource 83 across the line conductors l6 and I1. As indicated above, atthe even numbered intersections the amber lamps corresponding to andincluding the lamp 21a provided at the intersection 2 are energized whenthe relay 95 operates to impress the voltage of the source 83 across theline conductors l6 and H3. Thus, when the relay 50a embodied in thecontrol unit Illa provided at the intersection 2 operates, it completesa circuit for energizing the amber lamp 212., this circuit extendingfrom one terminal of the alternating current source by Way of theconductor 29a, the armature 5hr, the contact 52a, the armature 3h, thecontact 32a, the lamp 212, and the conductor 28a to the oppositeterminal of the current source. Similarly, when the relay 50c embodiedin the control unit We provided at the intersection 4 operates, itcompletes a circuit for energizing the amber lamp 2%, this circuitextending from one terminal of the alternating current source by way ofthe conductor 29c, the armature 51, the contact 52c, the armature 3b,the contact 320, the lamp 27c and the conductor 280 to the oppositeterminal of the current source. The concurrent energization of thesignal lamps 22, 24 and 26, respectively provided at the odd numberedintersections, and of the lamps 23, 25

' and 21, respectively provided at the even numbered intersections,persists for the time interval required for the wipers of the switch 60to traverse their respective eleventh and twelfth contacts. When thesewipers are moved out of en gagement with their associated twelfthcontacts and into engagement with their respective associated thirteenthcontacts, the relays T5, 85, 93 and 95 are deenergized, and the relaysand 99 are energized and operate. Thus, when the wiper 65 is moved outof engagement with its associated twelfth contact and into engagementwith its associated thirteenth contact, the relay [5 is deenergized andrestores to complete the operating circuit for the relay 8!), thiscircuit extending by way of the grounded Wiper 65, the multipledthirteenth to twenty-fourth contacts of the contact set 62, the armaturel6, and the winding of the relay 8!! to the negative terminal of thecurrent source 83. Similarly, when the wiper 66 disengages itsassociated twelfth contact and engages its associated thirteenthcontact, the operating circuit for the relay 85 is interrupted and thisrelay restores to complete the operating circuit for the relay 99, thelatter circuit extending by way of the grounded wiper 66, the multipledthirteenth to twenty-fourth contacts of the contact set 63, the armature85, and the winding of the relay 9!! to the negative terminal of thecurrent source 83. Likewise, the wiper 51, when operated out ofengagement with its associated twelfth contact, opens a point'in thepreviously traced operating circuit for the relay 95. Finally, the wiper5'5, when disengaged from the twelfth contact of the set 54, opens theoperating circuit for the relay 93.

When the relay l5 restores it opens, at its armature ll, a point in thepreviously described path by way of which the voltage of the source 18is impressed across the conductors l5 and E9 of the line circuit E5.Similarly, when the relay 85 restores it opens, at its armature Bl, apoint in the path by Way of which the voltage of the source '58 isimpressed across the line conductors l6 and it. The relay 95, uponrestoring, opens, at its armature 95, a point in the path by way ofwhich the voltage of the source 83 is impressed across the lineconductors l5 and H9. The relay 93, upon restoring, opens a point in thepath over which the voltage of the source 83 is impressed across theline conductors l6 and I1. When the relay 85 operates shortly followingthe restoration of the relay "55, it completes a path including thearmature 32 for impressing the voltage of the source 83 across theconductors l6 and E9 of the line circuit 115, this voltage beingoppositely poled with respect to that impressed across the sameconductors through operation of the relay E5. The relay 9%, uponoperating, similarly completes path including the armature 92 forimpressing the voltage of the source 83 across the line conductors l5and 59, this voltage also being of a polarity opposite that of thevoltage impressed across the same pair of conductors when the relay 85operates.

When the relay 93 and 95 restore in the manner just described, to openpoints in the paths by way of which the voltage of the source 83 isimpressed across the two pairs of line conductors 56, H and l6, l9, therelays 59, 59a, 59b, 59c, etc., respectively embodied in the controlunits ill, Illa, iflb, lilo, etc., are all deenergized and restored.Upon restoring, the relays 59 embodied in the control units located atthe odd numbered intersections function to open the operating circuitsfor the respective associated amber lamps 24. Thus, the relay 59,embodied in the control unit l9 located at the intersection l, uponrestoring, opens, at its armature 5! and the associated contact 52, apoint in the above-traced circuit for energizing the lamp 25. Similarly,the relay 59b embodied in the control unit lllb located at theintersection 3, upon restoring, opens, at the armature Me and itsassociated contact 52b, a point in the previously traced circuit forenergizing the amber lamp 24b. respectively embodied in the controlunits located at the even numbered intersections is similarly effectiveto cause the deenergization of the respective associated amber signallamps Z'l. Thus, the relay 59a embodied in the control unit Id providedat the intersection 2, upon restoring, opens, at its armature 5M and itsassociated contact 522., a point in the above-traced circuit forenergizing the amber lamp 218,. Similarly, the relay 5% embodied in thecontrol unit I50 located at the intersection 5, upon restoring, opens,at its armature 5h; and the associated contact 528 a point in thepreviously described circuit for energizing the amber lamp 270.

When the voltage of the current source 18 is removed from across theline. conductors l6 and 9, and the voltage of the source 83 is impressedacross these conductors, the relay 39a embodied in the control unit illsresponds by operating to The restoration of the relays 55 its secondoperating position to open, at its ar'ma- 75 ture 3|a and the associatedcontact 323. a further point in the circuit for energizing the amberlamp 21a. At its armature 3l2. and the associated contact 33a, the relaya prepares a circuit, traced hereinafter, for energizing the amber lamp24a. At its armature 34a and the contact a, the relay 35a opens a pointin the abovetraced circuit for energizing the red signal lamp 232, andthe green signal lamp 252.. At its armature 34s., the relay 302. alsocompletes a circuit for energizing the green signal lamp 223, inparallel with the red signal lamp 263., this circuit extending from oneterminal of the alternating current source by way of the conductor 29a,the armature 43s., the contact 452., the armature 3 h, the contact 369.,the two lamps 22a and 26a in parallel and the conductor 28a to theopposite terminal of the current source. Through the deenergization ofthe signal lamps 23a, and 25a and the energization of the lamps 22a. and26a, trafiic right of way is shifted from the cross highway Zia to themain or arterial highway 2! at the intersection 2. At the second evennumbered intersection 4', traffic right of way is also shifted from thecross highway 21c to the main highway 20 when the voltage of the source83 is substituted for the voltage of the source I8 upon the lineconductors I6 and I9. Thus, the relay 3% responds to this change in thepolarity of the voltage impressed across the indicated line conductorsby operating to its restored position to open, at its armature Me andthe associated contact 320 a further point in the above-traced circuitfor energizing the amber lamp 2%. At its armature 3-I c and theassociated contact 33, the relay 39c prepares a circuit, tracedhereinafter, for energizing the amber lamp 240. At its armature 34c andthe associated contact 350, the relay 30!: opens a point in theabove-described circuit for energizing the signal lamps 23c and 25c inparallel. At its armature 3%, the relay 30:: also completes a circuitfor energizing the lamps 22c and 26c in parallel, this circuit beingexactly similar to that just traced for the lamps 22a and 28a providedat the intersection 2. In a similar manner the relays corresponding tothe relays 353a and 30c respectively embodied in the other control unitsindividually provided at the other even numbered intersection are causedto operate to shift the traific right of way from the respectiveassociated cross streets to the main or arterial highway 28; Also, whenthe voltage of the source I8 is removed from across the line conductorsI6 and i8 and the voltage of the source 83 is impressed upon theseconductors, the relays 39, 30b, etc., respectively embodied in thecontrol units provided at the odd numbered intersections along thehighway 20, are all caused to restore. Upon restoring, the relay 38opens, at its armature 3! and the associated contact 32', a furtherpoint in the above-traced circuit for energizing the amber lamp 24. Atits armature 3! and the associated contact 33, the relay 39 prepares acircuit, traced hereinafter, for energizing the amber lamp 2]. At itsarmature 34 and the associated contact 35, the relay 38' opens a pointin the previously traced circuit for energizing the two lamps 22 and 26in parallel. At its armature 34, the relay 3|! also completes a circuitfor energizing the green signal. lamp 25 in parallel with the red signallamp 23 this circuit extending from one terminal of the alternatingcurrent source by way of the conductor 29, the armature 43, the contact45, the armature 34, the contact 36, the two lamps Hand 25 in parallel,and the conductor 28 to the opposite terminal of the current source.Thus, through the restoration of the relay 30, traific right of way istransferred at the intersection I from the main highway 20 to trafficproceeding along the cross highway 2 I. In a similar manner, trafficright of way is transferred from the main highway 28 to the crosshighways at each of the other odd numbered intersections. Thus, therelay Sflb provided in the control unit Illb located at the intersection3, upon restoring, opens, at its armature 3Ib and the associated contact32b, 21. further point in the circuit for energizing the amber lamp 2 3.At its armature tilt and the associated contact 33s, the relay 30bprepares a circuit, described hereinafter, for energizing the amber lamp27b. At its armature 34b and the contact 35b, the relay 30b opens apoint in the previously traced circuit for energizing the signal lamps22b and 26b in parallel. At its armature 3% andthe associated contact36b, the relay 36b, upon restoring, also completes a circuit forenergizin the red signal lamp 23b in parallel with the green signal lamp25b, this circuit being exactly similar to that traced above withreference to the corresponding lamps 23 and 25 located at theintersection I.

Since the thirteenth to twenty-fourth contacts of each or" the twocontact sets 62 and 63 are respectively multipled together, the relays80 and 913 are held operated during movement of the wipers 65' and 66over these contacts. Such movement of the switch wipers represents thesecond portion of each signaling cycle. It will be apparent that, duringthis movement of the switch wipers, the red signal lamps 23,respectively provided at the odd numbered intersections for giving stopindications to traffic proceeding along the highway 2t, and the greensignals 22, respectively provided at the even numbered intersections forgiving right-of-way indications to traffic proceeding along the highway20, are concurrently energized. During the last part of the secondportion of the signaling cycle under consideration, and when the wipersEl and 67' are moved into engagement with their respective associatedtwentythird contacts, alternative circuits are completed for energizingthe relays 93 and 95, whereby the amber lamps 2'! provided at the oddnumbered intersections and the amber lamps 24 provided at the evennumbered intersections are energized. The circuit for energizing therelay 95 may be traced as extending by way of the grounded wiper 51, themultiple twenty-third and twenty-fourth contacts of the set 64, and thewinding of the relay 95 to the negative terminal of the current source83, and the circuit for energizing the relay 93 may be traced asextending by way of the grounded wiper 61, the multipled twenty-thirdand twenty-fourth contacts of the set 6%, the switch springs I13 andIIZ,and the winding of the relay 93 to the negative terminal of the source33. When energized over circuits just traced, the relays 93 and 95 againoperate to impress the voltage of the source 83 across the two pairs ofconductors I6, I! and IS, IS of the line circuit 15. The relays 50, 59a,50b, 50c, etc., respectively embodied in the various control unitscontrolled over the line circuit I5 all operate when the voltage of thesource 83 is impressed across the indicated line conductors. The relay5! embodied in the control unit It located at the intersection i, uponoperating, functions to complate the circuit for energizing the ambersignal lamp 21, this circuit extending from one terminal of the currentsource by way of the. conductor 29,

the armature 5|, the contact 52, the armature 3 I, the contact 33, thelamp 27, and the conductor 28 to the opposite terminal of the currentsource. In a similar manner, the amber lamps 21 respectively located atthe other odd numbered intersections are energized in response to thelast-described application of control voltage to the line conductors I6and I9. Thus, the relay 50b, upon operating, completes, at its armaturebib and the contact 52b associated therewith, a circuit for energizingthe amber lamp 2Tb, which circuit is exactly similar to that just tracedwith reference to the amber lamp 2'! provided at the intersection I. Therelay 50a embodied in the control unit Iila located at the even numberedintersection 2, upon operating, functions to complete a circuit forenergizing the amber lamp 24a, this circuit extending from one terminalof the current source by way of the conductor 2%, the armature 5b, thecontact 52a, the armature SIa, the contact 33a, the lamp 24a, and theconductor 28a to the opposite terminal of the current source. The relay50 embodied in the control unit Illa likewise completes a circuit forenergizing the amber lamp 240, which circuit is exactly similar to thecircuit for energizing the lamp 24a provided at the intersection 2. In asimilar manner, the amber lamps 24 respectively provided at the othereven numbered intersections along the highway 25 are energized duringthe last part of the second portion of the signaling cycle.

The concurrent energization of the lamps 23, 25 and 21 provided at theodd numbered intersections and of the lamps 22, 26 and 24 provided atthe even numbered intersections persists until the second portion of thesignaling cycle is completed or, more particularly, until the wipers ofthe switch 68 are operated out of engagement with their respectiveassociated twenty-fourth contacts and into engagement with their respective associated first contacts. Thus, when the wipers 61 and 61' aremoved out of engagement with their associated twenty-fourth contacts,the above-traced alternative operating circuits for the relays 95 and 93are interrupted, and these relays restore to cause the deenergization ofthe relays 58, 50a, 59b, 500, etc, respectively embodied in the controlunits associated with the line circuit I5. As a result, the lightedamber lamps at the various intersections are all dcenergized. When thewiper 65 is moved out of engagement with its associated twenty-fourthcontact and back into engagement with its associated first contact, theabove-traced operating circuit for the relay 8B is interrupted, causingthis relay to restore to recompletes, at its armature BI, the previouslytraced operating circuit for the relay I5. Thus, the voltage of thesource 83 is removed from across the line conductors I5 and I9, and thevoltage of the source 78 is again impressed between these conductors.Similarly, when the wiper 66 is moved out of engagement with itsassociated twenty-fourth contact and back into engagement with itsassociated first contact, the operating circuit for the relay 9i) isinterrupted and this relay restores to complete, at its armature 9 I,the previously traced operating circuit for the relay85. Through therestoration of therelay9ll and the subsequent operation of the relay 85,the voltage of the source 83 is removed from across the line conductorsI6 and I8 and the voltage of the source 58 is again impressed thereon.When the voltage of the source '58 is impressed across the two pairs ofconductors I6, I8 and i6, I9 of the line circuit I5, the relays 30, 30a,30b, 30c, etc., re-

spectively embodied in the control units I0, Illa, Ills, Illa, etc,associated with the line circuit I5, all operate. Upon operating, therelay 30 opens, at its armature IN and the contact 33, a further pointin the circuit for energizing the amber signal lamp 21, and prepares, atits armature 3| and the contact 32, the previously traced circuit forenergizing the amber signal lamp 24. At its armature 34 and the contact36, the relay 3!] opens the above-traced circuit for energizing thesignal lamps 23 and 25 in parallel and recompletes the previously tracedcircuit for energizing the lamps 22 and 26 in parallel. Thus,trafiicright of way is transferred from the cross highway 2| to the mainhighway 20 to start the first portion of a second signaling cycle. In asimilar manner, traffic right of way is transferred from the crosshighways to the main highway 20 at each of the other odd numberedintersections along the highway 28. Thus, the relay 3% embodied in thecontrol unit IIlb located at the intersection 3, upon operating, opens,at its armature 3Ib and the contact 33b, a further point in thepreviously described circuit for energizing the amber lamp 21b andreprepares, at its armature 3h. and the contact 32b, the above-describedcircuit for energizing the amber lamp 2%. At its armature Mb and thecontact 36b, the relay 38b opens the circuit for energizing the lamps23b and 25b in parallel. Finally, at the armature 34b and the contact35b, the relay 3% recompletes the previously described circuit forenergizing the lamps 22b and 26b in parallel. At the even numberedintersections, trafiic right of way is transferred from the main orarterial highway 2Q to the cross highways. Thus, when the relay 3%embodied in the control unit Illa located at the intersection 2operates, it opens, at its armature 3 la and the associated contact 33a,a further point in the circuit for energizing the amber lamp 24a, andprepares, at its armature 3Ia and the contact 32a, the previously tracedcircuit for energizing the amber lamp 21a. At its armature 34a and thecontact 36a, the relay 39a opens the circuit for energizing the greenlamp 22a in parallel with the red lamp 26a. At the armature 3% and thecontact 35a, the relay 30a, upon operating, also completes thepreviously traced circuit for energizing the lamps 23a and 25a inparallel. Similarly, when the relay 3% embodied in the control unit I00located at the intersection 4 assumes its first operating position, itopens, at its armature 3 I0 and the associated contact 33, a furtherpoint in the circuit for energizing the amber lamp 24c, and reprepares,at its I armature 3Ic and the contact 320, the circuit for energizingthe amber signal lamp 270. At its armature 3 lc and the associatedcontact 360, the relay 3% interrupts the circuit for energizing thesignal lamps 22c and 28 in parallel. At its armature 3lc and theassociated contact 35c, the relay 3Ic also completes the previouslydescribed circuit for energizing the signal lamps 23c and 25 inparallel. Thus, traffic right of way is shifted from the cross highwaysto the main highway 20 at the odd numbered intersections and from themain highway 20 to the cross highways at the even numberedintersections, and a second sig-' naling cycle is started, From thispoint on, the manner in which the signal lamps provided at the variousintersections are sequentially energized during the respective portionsof each succeeding signaling cycle is exactly the same as switch 85 isprovided for the purpose of dividing each signaling cycle, as describedabove, into three portions. After this switch is operated to itsoii-normal position, the green signal lamps for giving right-of-wayindications to trafi'ic proceeding along the highway 2! are concurrentlyenergized at all of the intersections for the first por tion of eachsignaling cycle. During the second portion of each cycle, the greensignal lamps for giving right-of-way indications at the even numberedintersections to trafiic proceeding along the main highway 28 areoperated concurrently with the main highway red or stop signal lamps atthe odd numbered intersections. During the third portion of each cycle,the main highway stop signals at the even numbered intersections areoperated concurrently with the main highway right of way signals at theodd numbered intersections. More particularly, when the switch 99 isoperated from its normal position, illustrated in the drawings, to theofi-normal position, the movable contact spring N39 is moved out ofengagement with its associated spring ill! and into engagement with thespring N33 to disconnect the multipled first and second contacts of thecontact set 62 from the multipled third to twelfth contacts of this set,andto connect the multipled first and second contacts to the multipledthirteenth to twenty-fourth contacts of the set 62. Also, when theswitch 99 is operated-to its off-normal position, the movable contactspring I I2 is moved out of engagement with the contact spring H! andinto engagement with the contact spring l l3. As a consequence, theoperating circuit for the relay 93, which governs the energization ofthe amber lamps provided at the respective even numbered intersections,is, during the first portion of each signaling cycle, completed when thewiper 6T traverses its associated first and second contacts. Hence,during the third portion of each signaling cycle, the relays 5Ba, 500,etc., respectively embodied in the control units provided at the evennumbered intersections, are energized to cause the energization of theamber lamps 24a, 2%, etc., throughout the interval when the wiper iil'traverses the first and second contacts of the contact set 64', ratherthan during movement of this wiper over its associated twentythird andtwenty-fourth contacts. Thus, the energization of the amber lamps 24provided at the even numbered intersections 2, 4, etc., is advanced sothat it overlaps the last part of each period during which the greenlamps 22 provided at the even numbered intersections are energized.

With the switch 99 operated to its ofi-normal position and when thewipers of the switch 66 are stepped out of engagement with theirrespective associated twenty-fourth contacts and into engagement withtheir respective associated first contacts, the above-traced operatingcircuit for the relay 95 is interrupted at the wiper 61, and this relayrestores to cause the lighted amber lamps 2i, provided at the oddnumbered intersections, to be deenergized in the manner previouslyexplained. When the wiper 66 is moved out of engagement with itsassociated twentyfourth contact and back into engagement with itsassociated first contact, the operating circuit for the relay 961 isinterrupted and this relay restores to recompletethe operating circuitfor the relay 85. Thus, the lamps 23 and 25, provided at the oddnumbered intersections, are deenergized, and the lamps 22 and 26,provided at the odd numbered intersections. are again energized, all inthe manner previously explained. When the wiper 65 is stepped out ofengagement with its associated twenty-fourth contact and into engagementwith its associated first contact, the relay 8!! is maintained energizedover the previously described circuit which now includes the multipledfirst and second contacts of the set 62. Hence, the relays 3%, 3%, etc.,embodied in the control units provided at the even numberedintersections 2, 4, etc., are maintained in positions such that thecircuits are energizing the signal lamps 22a and 26a, provided at theeven numbered intersections, are held energized. Thus, traffic right ofway is not transferred from the main or arterial highway 20 to the crosshighways 2's, and 21. When the wiper B1 is stepped into engagement withits associated first contact, an alternative circuit is completed forenergizing the relay 93, this circuit extending by way of the groundedwiper 6?, the switch springs H! and l l2, and the winding of the relay93 to the negative terminal of the current source 83. The relay 93 nowoperates to again impress the voltage of the source 83 across the lineconductors l6 and I! with the result that the relays 58a, 500, etc.,respectively embodied in the control units provided at the even numberedintersections, all operate to complete the circuits for energizing theirrespective associated amber lamps 24a, 2%, etc. The energization of thelamps 22, 2d and 26, provided at the respective even numberedintersections continues. until the wipers of the switch 60 are operatedout of engagement with their respective associated second contacts andinto engagement with their respective associated third contacts, atwhich time the relays 8i! and 93 restore, and the relay [5 reoperates.When the relay 93 restores, the amber lamps 24, respectively provided atthe even numbered intersections are deenergized in the manner previouslyexplained. Also, when the relay 80 restores and the relay '!5reoperates, traffic right of way at the even numbered intersections istransferred from the main highway 20 to the cross highways in the mannerpreviously described.

From the foregoing description, it will be apparent that, if the switch99 is operated from its off-normal position back to its normal position,the third portion of each signaling cycle, namely, that during which themain highway green signal lamps are all energized, is eliminated fromthe signaling cycle, and the first portion of each cycle is extended toinclude the time interval of the third portion of the correspondingcycle. More particularly, when the switch 99 is returned to its normalposition, the amber signal lamp control relay 93 is operated'to causethe energization of the amber lamps 2 provided at the even numberedintersections during the period of each signaling cycle when the wiper61 traverses its associated twenty-third and twentyfourth contacts.Also, the first and second contacts of the set 62 are again included inthe multiple by way of which the relay (5 is energized. Hence, trafficright-of-way indications, occasioned by operation of the signal lamps,are equally divided between the cross highways and the main highway andthe system again operates on a straightforward two phase basis.

As previously indicated, operation of the switch 9'! is efiective tochange the elapsed time interval of each signaling cycle. Moreparticularly, with the springs of the switch 9? occupying the positionsillustrated in the drawings, the operating magnet 68 of the switch 66 isenergized in accordance with the pulses of slow rate impressed upon theconductor 69 by the pulse generator 6|. When, however, the movablespring I0! is operated out of engagement with the associated spring I00and into engagement with the spring I92, the magnet 68 is connected tobe energized in accordance with the fast pulses impressed upon theconductor 10 by the generator 6|. As a result the elapsed time intervalof each signaling cycle is materially reduced. If desired, a clockdriven circuit changer may be substituted for the manually operableswitch 91, whereby the magnet 68 is connected to be energized inaccordance with the pulses of slow rate. during certain periods of theday when heavy trafiic conditions exist, and to be energized inaccordance with the pulses of fast rate during the remaining portions ofthe day when light trafilc conditions exist.

When the night switch 98 is operated from its normal position, asillustrated in the drawings, to its ofi-normal position, the contactsprings I06 and I9! embodied therein are disengaged to open a point inthe previously traced operating circuit for the magnet 68. Thus, theoperation of the rotary switch 60 is arrested. At the springs I 03 and104, a point is opened in the above-described path over which thevoltage of the current source 83 is impressed across the line conductorsl6 and I9. At the springs H4 and H5, a point is opened in theabove-described path over which the voltage of the current source 83 isimpressed across the line conductors l6 and I1. At the springs I04 andH15, an obvious path is completed for impressing the voltage of thecurrent source 18 across the line conductors H5 and 19', this voltagebeing of a polarity opposite that of the voltage of the source 83 asimpressed across the same line conductors. At the springs I I5 and H6,an obvious path is completed for impressing the voltage of the source 78across the line conductors l5 and H. When the terminals of the currentsource 18 are connected to the line conductors I 6, I! and IS in themanner just described the polarized relays 40, 40a, 40b, Me, etc.,respectively embodied in the various control units associated with theline circuit l5 all operate. When the relay 40 embodied in the controlunit l0 operates, it opens, at its armature 43 and the associatedcontact $5, a point in the common portion of the previously tracedcircuits for energizing the signal lamps 22, 23, 25, and 26 located atthe intersection 1, thereby to extinguish the ones of these lamps whichare energized at the time the switch 98 is operated to its off-normalposition. At the armature 43 and its associated contact 46, an obviouscircuit is completed for energizing the amber lamp 21. Finally, at itsarmature M and the contact 42 associated therewith, the relay 40completes an obvious circuit for energizing the amber lamp 224. Thus,when the relay 49 operates, the red and green lamps provided at theintersection I are all deenergized, and the amber lamps 24 and 21 areenergized to display caution signals in each of the four trafiicapproach directions. In a similar manner, the red and green lampsprovided at each of the other intersections are all deenergized, and theamber lamps are energized to display caution signals to trafiicproceeding in the four traffic approach directions. Obviously, when theswitch 98 is restored to its normal position, the amber lamps providedat the respective intersections are all deenergized and the normaloperation of the system is resumed.

Referring now particularly to Fig. 4 of the drawings, the charts thereillustrated graphically portray the manner in which the system, asdescribed above, operates. More particularly, the chartA depicts theperformance characteristics of the system when the three switches 91, 98and 99 occupy their normal positions as illustrated in the drawings.operating characteristics of the system when the switch 91 is aloneoperated to increase the rate of the pulses transmitted to the operatingmagnet 68 of the cyclically operating control switch 60..

The chart C illustrates the operating characteristics of the system whenthe switch 99 is alone operated to its off-normal position. Finally, thechart D illustrates the operating characteristics of the system whenboth the switches 91 and 99 3 are operated to their respectiveoff-normal positions. From a consideration of the chart A it will beobserved that, during the first half of each signaling cycle, the greensignal lamps for giving right-of-way indications to traflic proceedingalong the main highway and located at the oddnumbered intersections areenergized concurrently with the main highway red or stop signal lamps atthe even numbered intersections.

During the second half of each signaling cycle,

on the other hand, the main highway red or stop signals at the oddnumbered intersections are energized concurrently with the main highwayright of way signals at the even numbered intersections. the progressiveform of control with respect to trafiic moving east along the mainhighway 20 and the diagonal lines c'and 11 indicate the progressive formofcontrol with respect to traflic moving west alongthe highway 20. theintersections to be spaced apart by equal distances, the slopes of thediagonal lines are indicative of the average speeds which must bemaintained by blocks of trafiic in order for movement of the traffic tobe synchronized with the progressive energization of the main highwayright-of-way signals. Thus, if a vehicle traveling east along thehighway 20 enters the intersection l the instant trafiic right of way isshifted from the highway 2| to thehighway 29, it must maintain a speedsuch that the time interval 9 elapses of right of way from the mainhighway 20 to the cross highway 2|, it must maintain a speed such thatthe distance between the intersections l and 2 is traversed during thetime interval 1, or be stopped at the intersection 2. Since the slope ofthe line b is proportional to the time interval 1, it is alsoproportional to the speed which the second vehicle, mentioned above,must maintain if its movement is to remain synchronized with theprogressive energization of the main highway right-of-waysignals. Itwill be observed that the slopes of the diagonal lines a, b, c and d areequal and it follows, therefore, that traffic is moved in each of thetwo directions along the main highway 20 with equal facility. It will beobserved further that the slope of the indicated diagonal lines is notparticularly steep and, hence, relatively long time intervals areprovided for vehicles to move along the main highway 20 betweensucceeding intersections without falling The diagonal lines av and bindicate The chart B represents the X out of stepwith the progressiveenergization of the main highway right-of-way signals. Such relativelylong time intervals are desirable when conditions of heavy traflicdensity prevail. On the other hand, when trafiic along the main highwayis light, vehicles may move at a much higher rate of speed withcomparative safety. It is to accommodate this different condition thatthe switch 91 is provided in the above-described system. From the chartB it will be observed that, when this switch is operated to itsoff-normal position, the time interval of each signaling cycle ismaterially reduced with the result that the slope of each of the linesa, b, c and d is materially steepened. This increased slope indicatesthat the average speed of a vehicle traveling along the highway 20 ineither direction must be materially increased if the movement of thevehicle is to be synchronized with the progressive energization of themain highway right-of-way signals.

If, during a period of heavy traffic density, obstructions to trafiicflow in along the highway Zlloccur at spaced points therealong, as aresult of bus stops or the like, the tr'afiic flow is temporarilyimpeded at the points of obstruction with the result that the movementof trafiic may temporarily fall out of step with the progressiveenergization of the main highway right-of-way signals at such points anddelays are incurred before the normal movement of traffic is againresumed. In order to obviate this difficulty, the manually operableswitch 99 is provided in the system. From a consideration of the chartsC and D, it will be observed that, when this switch is operated to itsoff-normal position, each period during which the main highway right-of-Way signals at the even numbered intersections are energized is extendedto overlap for the time interval 9 the period during which the mainhighway right-of-way signals at the odd numbered intersections areenergized. As a result, the slope of the line b is decreased and thenincreased during each signaling cycle from the slope .of the line ashown in the chart A. Hence, an increased time interval is allotted forthe movement of vehicles over each alternate traffic lane section. Thesame time interval, namely, the interval e, is alotted for movement ofvehicles over the space of each intervening traffic lane section. Bythus staggering the time intervals allotted for traific movement overalternate ones of the traific lane sections, a greater flexibility inthe speed of the traffic is achieved eventhough the average speed whichmust be maintained by the trafiic is not changed.

Although the system has been described with reference to the use ofpolarized relays of the parmanent magnet stay put or toggle type, itwill be understood that the system may, but with slight modification, beadapted to the use of simple non-polarized relays in each of the controlunits. Thus, if the relays indicated at 30 and individually provided ineach of the control units are of the non-polarized type, the relays 80and 90 and the respective control circuits therefor may be omitted fromthe system. With such an arrangement, each non-polarized relay 30 willassume its operated position when voltage isimpressed across the lineconductors to which its winding is connected, and will assume itsrestored position when the indicated voltage is removed from the lineconductors, thus effecting the required switching operations. It willfurther be apparent that, in the illustrated system where.

in the control relays 30 are of the stay put or toggle type, themultiples described previously 'with reference to the contact sets 82and 63 may be omitted so that the indicated relays 30 are only energizedat the beginning of each portion of each signaling cycle.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be understood thatvarious 1 modifications may be made therein, and it is intended to coverin the appended claims all such modifications as fall within the truespirit and scope of the invention.

What is claimed is:

In a tram? signaling system for a traffic lane having a plurality oftraflic intersections therealong, signals at said intersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, and apparatus for auto:

matically operating said signals in accordance with a predeterminedsignaling cycle comprising only three portions; said apparatuscomprising means for operating the right-of-way signals at alternateintersections and the stop signals at.

the intervening intersections concurrently for one portion of eachsignaling cycle, means for operating the stop signals at said alternateintersections and the right-of-way signals at said interveningintersections concurrently for a second portion of each signaling cycle,means for having a plurality of traffic intersections therealong,signals at said intersections for giving right-of-way, caution and stopindications to traffic proceeding along said lane, and apparatus forautomatically operating said signals in accordance with a predeterminedsignaling cyclecomprising only three portions; said apparatus comprisingmeans for operating the right-of-way signals at alternate intersectionsand the stop signals at the intervening intersections concurrently forone portion of each signaling cycle,

means for operating the caution signals at said alternate intersectionsconcurrently with the right-of-way signals at said alternateintersections for an interval during the last part of said one portionof each signaling cycle, means for '55 operating the stop signals atsaid alternate intersections and the right-of-way signals at saidintervening intersections concurrently for a second portion of eachsignaling cycle, means for operating the right-of-way signals at all ofsaid intersections concurrently for the third portion of each signalingcycle, and means for operating the caution signals at said interveningintersections for at least a part of said third portion of eachsignaling cycle; means for eliminating said third portion of eachsignaling cycle and for extending one of said one and said secondportions of each signaling cycle to include said third portion of thecorresponding cycle, and

means operative concurrently with said lastmentioned means for changingthe part of each signaling cycle during which the caution signals atsaid intervening intersections are operated.

3. In a traflic signaling system for a traflic lane having a pluralityof trafiic intersections there-'75 along, signals for givingright-of-way and stop indications to traffic proceeding along said lane,a control unit at each intersection for controlling the operation of thesignals at the associated intersection, a line interconnecting saidunits, a master unit for controlling said control units over said linein accordance with a predetermined signaling cycle such that the stopand right-of-way signals at each intersection are operated for portionsof each signaling cycle, and means included in said master unit forcontrolling the control units at alternate intersections over said linecircuit to change the percentage of each signaling cycle during whichthe right-of-way signals at said alternate intersections are operatedwithout changing the percentage of each signaling cycle during which theright-of-way signals at the intervening intersections are operated.

4. In a traffic signaling system for a trafiic lane having a pluralityof traflic intersections therealong, signals at said intersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonductor line circuit interconnecting said control units, a masterunit for controlling said control units over said line circuit so thatsaid signals are energized in accordance with a predetermined signalingcycle; said master unit comprising means for concurrently impressingcontrol voltages across two pairs of the conductors of said line circuitfor one portion of each signaling cycle, means for removing said controlvoltages from said pairs of conductors for a second portion of eachsignaling cycle, and means for impressing one of said control voltagesacross one of said pairs of conductors for a third portion of eachsignaling cycle; means individually included in a portion of saidcontrol units and operative in response to the control voltage impressedacross one of said pairs of conductors for causing the energization ofthe right-of-way signals at the respective associated intersections,said last-named means being operative to cause the energization of thestop signals at the respective associated intersections when saidlastmentioned control voltage is removed from across said last-namedpair of conductors, and means individually included in the remainingportion of said control units and operative in response to the controlvoltage impressed across the other of said pairs of conductors forcausing the energization of the stop signals at the respectiveassociated intersections, said last-named means being operative to causethe energization of the right-of-way signals at the respectiveassociated intersections when said last-mentioned control voltage isremoved from across said other pair of conductors.

5. In a trafiic signaling system for a traffic lane having a pluralityof traific intersections therealong, signals at said intersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonducto-r line circuit interconnecting said con trol units, amaster unit for controlling said control units over said line circuit sothat said signals are energized in accordance with a predeterminedsignaling cycle; said master unit comprising means for concurrentlyimpressing control voltages across two pairs of the conductors of saidline circuit for one portion of each signaling cycle, means for removingsaidcontrol voltages from said pairs of conductors for a second portionof each signaling cycle, and means for impressing one of said controlvoltages across 5 one of said pairs of conductors for a third portion ofeach signaling cycle; means individually included in a portion of saidcontrol units and operative in response to the control voltage impressedacross one of said pairs of conductorsdO for causing the energization ofthe right-of-way signals at the respective associated intersections,said last-named means being operative to cause the energization of thestop signals at the respective associated intersections when said last-5 mentioned control voltage is removed from across said last-named pairof conductors, means individually included in the remaining portion ofsaid control units and operative in response to the control voltageimpressed across the other of saidu20 pairs of conductors for causingthe energization of the stop signals at the respective associatedintersections, said last-named means being operative to cause theenergization of the right-of-way signals at the respective associatedintersections when said last-mentioned control voltage is removed fromacross said other pair of conductors. and means included in said masterunit for rendering said third-named means inactive, thereby to eliminatesaid third portion of each signaling cycle.

6. In a traflic signaling system for a traflic lane having a pluralityof traflic intersections therealong, signals at said intersections forgiving right-of-Way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonductor line circuit interconnecting said control units, a masterunit for controlling said control units over said line circuit so thatsaidv signals are energized in accordance with a predetermined signalingcycle; said master unit comprising means for impressing control voltagesof predetermined polarities across two pairs of conductors of said linecircuit at the beginning of one portion of each signaling cycle, meansfor impressing control voltages of opposite polarities across said twopairs of conductors at the beginning of a second portion of eachsignaling cycle, and means for impressing only one of saidfirstmentioned control voltages across only one of said pairs ofconductors at the beginning ofa third portion of each signaling cycle;means individually included in certain of said control units, andoperative in response to control voltages of one of said predeterminedpolarities impressed on one of said pairs of conductors for causing theenergization of the right-of-way signals at the respective associatedintersections, means indi-, vidually included in said last-mentionedcontrol units and operative in response to control voltage of theopposite polarity impressed across said last-mentioned pair ofconductors for causing the energization of the stop signals at saidlast-, mentioned intersections, means individually included in others ofsaid control units and operative in response to control voltage of theother of said predetermined polarities impressed across the other ofsaid pairs of conductors for causing 7 the energization of the stopsignals at the intersections respectively associated with said othercontrol units, and means individually included in said other controlunits and responsive to control voltage of the opposite polarityimpressed acrossqzg said other pair of conductors for causing theoperation of the right-of-way signals at the intersections respectivelyassociated with said other control units.

7. In a trafiic signaling system for a traffic lane having a pluralityof traffic intersections 'therealong, signals at said intersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonductor line circuit interconnecting said control units, a masterunit for controlling said control units over said line circuit so thatsaid signals are energized in accordance with a predetermined signalingcycle; said master unit comprising means for impressing control voltagesof predetermined polarities across two pairs of conductors of said linecircuit at the beginning of one portion of each signaling cycle, meansfor impressing control voltages of opposite polarities across said twopairs of conductors at the beginning of a second portion of eachsignaling cycle, and means for impressing only one of saidfirstmentioned control voltages across only one of said pairs ofconductors at the beginning of a third portion of each signaling cycle;means individually included in certain of said control units andoperative in response to control voltages of one of said predeterminedpolarities impressed on one of said pairs of conductors for causing theenergization of the right-of-way signals at the respective associatedintersections, means individually included in said last-mentionedcontrol units and operative in response to control voltage of theopposite polarity impressed across said last-mentioned pair ofconductors for causing the energization of the stop signals at saidlast-mentioned intersections, means individually included in others ofsaid control units and operative in response to control voltage of theother oil said predetermined polarities impressed across the other ofsaid pairs of conductors for causing the energization of the stopsignals at the intersections respectively associated with said othercontrol units, means individually included in said other control unitsand responsive to control voltage of the opposite polarity impressedacross said other pair of conductors for causing the operation of theright-ofway signals at the intersections respectively associated withsaid other control units, and means included in said master unit forrendering said third-named means inactive, thereby to eliminate saidthird portion of each signaling cycle.

8. In a traiflc signaling system for a traific lane having a pluralityof traflic intersections there- :along, signals at said intersectionsfor giving rightof-way and stop indications to traffic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulti-conductor line circuit interconnecting said control units, amaster unit for controlling said control units over said line circuit sothat said signals are energized in accordance with a predeterminedsignaling cycle; said master unit comprising means for impressingcontrol voltages of one character across each of two pairs of conductorsat the beginning of one portion of each signaling cycle, means forimpressing control voltages of different character across each of saidtwo pairs of conductors at the beginning of a second portion of eachsignaling cycle, and means for impressing one of said firstmentionedcontrol voltages across one of said pairs of conductors and one of saidsecond mentioned control voltages across the other of said pairs'ofconductors at the beginning of a third portion of each signaling cycle;relays individually included in certain of said control units and eachoperative to one position in response to control voltage of said onechaarcter impressed across one of said pairs of conduotorsand to asecond position in response to control voltage of said differentcharacter impressed across said last-mentioned pair of conductors, saidrelays each being operative toresponse to control voltage of saiddifferent char- 20 acter impressed across said last-mentioned pair ofconductors, said additional relays each being operative to cause theenergization of the associated stop signal when operated to said oneposition and to cause the energization of the asso-' ciated right-of-waysignal when operated to said second position.

9. In a traffic signaling system for a traffic lane having a pluralityof trafiic intersections therealong, signals at said intersections forgiving rightof-way and stop indications to traflic proceeding along saidlane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonductor line circuit interconnecting said control units, a masterunit for controlling said control units over said line circuit so thatsaid signals are energized in accordance with a predetermined signalingcycle; said master unit comprising means for impressing controlvoltages.

of one character across each of two pairs of conductors at the beginningof one portion of each signaling cycle, means for impressing controlvoltages of different character across each of said two pairs ofconductors at the beginningof a second portion of each signaling cycle,and means for impressing one of said first-mentioned control voltagesacross one of said pairs of conductors and one of said second-mentionedcontrol voltages across the other of (said pairs of conductors at thebeginning of a third portion or each signaling cycle; relaysindividually included in certain of said control units and eachoperative to one position in response to control voltage of said onecharacter impressed across one of said pairs of conductors and to asecond position in response to control voltage of said differentcharacter impressed across said lastmentioned pair of conductors, saidrelays each being operative to cause the energization of the associatedright-of-way signal when operated to said one position and to cause theenergization of the associated stop signal when operated to said secondposition, additional relays individually included in others of saidcontrol units and each operative to one position in response to controlvoltage of said one character impressed across the other of said pairsof conductors and to a second position in response to control voltage ofsaid different character impressed across said last-mentioned pair ofconductors, said additional relays each being operativeto cause theenergization of the associated stop signal when operated to said oneposition and to cause the energization of the associated rightof-way-signal when operated to said second position, and means included insaid master unit for rendering said third-named means inactive, therebyto eliminate said third portion of each signaling cycle.

10. In a traflic signaling system for a traffic lane having a pluralityof trafiic intersections therealong, signals at said intersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonductor line circuit interconnecting said control units, a masterunit for controllingsaid control units over said line circuit so thatsaid signals are energized in accordance with a predetermined signalingcycle; said master unit comprising means for concurrently impressingcontrol voltages across two pairs of conductors of said line circuit forone portion of each signaling cycle, means for removing said controlvoltages from said pairs of conductors for a second portion of eachsignaling cycle, and means for impressing one of said control voltagesacross only one of said pairs of conductors for a third portion of eachsignaling cycle; relays individally included in certain of said controlunits and each operative to one position in response to control voltageimpressed across one of said pairs of conductors and to a secondposition when said control Voltage is removed from said last-mentionedpair of conductors, said relays each being operative to cause theenergization of the associated rightof-way signal when operated to saidone position and to cause the energization of the associated stop signalwhen operated to said second position, and additional relaysindividually included in others of said control units and each operativeto one position in response to control voltage impressed across theother of said pairs of conductors and to a second position when saidcontrol voltage is removed from said last-mentioned pair of conductors,said additional relays each being operative to cause the energization ofthe associated stop signal when operated to said one position and tocause the energization of the associated right-of-way signal whenoperated to said second position.

11. In a trafiic signaling system for a trafiic lane having a pluralityof traftlc intersections therealong, signals at said intersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, amulticonductor line circuit interconnecting said control units, a masterunit for controlling said control units over said line circuit so thatsaid signals are energized in accordance with a predetermined signalingcycle; said master unit comprising means for concurrently impressingcontrol voltages across two pairs of conductors of said line circuit forone portion of each signaling cycle, means for removing said controlvoltages from said pairs of conductors for a second portion of eachsignaling cycle, and means for impressing one of said control voltagesacross only one of said pairs of conductors for a third portion of eachsignaling cycle; relays individually included in certain of said controlunits and each operative to one position in response to control voltageimpressed across one of said pairs of conductors and to a secondposition when said control voltage is removed from said last-mentionedpair of conductors, said relays each being operative to cause theenergization of the associated right-of-way signal when operated to saidone position and to cause the energization of the associated stop signalwhen operated tosaid second position, additional relays individuallyincluded in others of said control units and each operative to oneposition in response to control voltage impressed across the other ofsaid pairs of conductors and to a second position when said controlvoltage is removed from said last-mentioned pair of conductors, saidadditional relays each being operativeto cause the energization of theassociated stop signal when operated to said one position and to causethe energization of the associated right-of-way signal when operated tosaid second position, and means included in said master unit forrendering said third-named means inactive, thereby to eliminate saidthird portion of each signaling cycle.

12. In a tra flic signaling system for a traffic lane having a pluralityof traflic intersections therealong, signals at saidintersections forgiving right-of-way and stop indications to trafiic proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, a linecircuit interconnecting said control units,,a master unit forcontrolling said control units over said line circuit so that saidsignals are energized in accordance with a predetermined signalingcycle, said control units individually comprising relays having twocorresponding operating positions, the relays included in certain ofsaid control units each being operative to one of said two positions tocause the energization of the associated right-of-way signal and to theother of said two positions to cause the energization oi the associatedstop signal, the relays included in others of said units each beingoperative to said one position to cause the energization of theassociated stop signal and to said other position to cause theenergization of the associated right-of-way signal, and means includedin said master unit for controlling said relays over said line circuitto cause said relays to operate between said two positions insynchronism at least once during each signaling cycle.

13. In a traflic signaling system for a traflic lane having a pluralityof trafiic intersections therealong, signals at said intersections forgiving right-of-way and stop indications to traillc proceeding alongsaid lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, a linecircuit interconnecting said control units, a master unit forcontrolling said control units over said line circuit so that saidsignals are energized in accordance with a predetermined signalingcycle, said control units individually comprising relays having twocorresponding operating positions, the relays included in certain ofsaid control units each being operative to one of said two positions tocause the energization of the associated right-of-waysignal and to theother of said two positions to cause the energization of the associatedstop signal, the relays included in others of said units each beingoperative to said one position to cause the energization of theassociated stop signal and to said other position to cause theenergization of the associated right-of-way signal, means included insaid master unit for controlling said relays over said line circuit tocause said relays to operate between said two positions in synchronismat least once during each signaling cycle, and means included in saidmaster unit for controlling said relays over said line circuit to causeeach of the relays respectively included in said certain control unitsto occupy one of said two positions'and each of the relays respectivelyincluded in said other control units to occupy the other of said twopositions concurrently for a portion of each signaling cycle.

14. In a traffic signaling system for a traflic lane having a pluralityof traflic intersections therealong, signals at said intersection forgiving right-of-way, caution and stop indications to trailic proceedingalong said lane, a control unit at each intersection for controlling theenergization of the signals at the associated intersection, a linecircuit interconnecting said control units, a master unit forcontrolling said control units over said line circuit so that saidsignals are energized in accordance with a predetermined signalingcycle, said control units individually comprising relays having twocorresponding operating positions, the relays included in certain ofsaid control units each being operative to one of said two positions tocause the energization of the associated right-of-way signal and to theother of said two positions to cause the energization of the associatedstop signal, the relays included in others of said units each beingoperative to said one position to cause the energization of theassociated stop signal and to said other position to cause theenergization of the associated right-of-way signal, means included insaid master unit for controlling said relays over said line circuit tocause said relays to operate between said two positions in synchronismat least once during each signaling cycle, said control unitsindividually including additional relays each operative to cause theenergization of the associated caution signal, and means included insaid master unit for controlling said additional relays over said linecircuit to cause each of said additional relays to operate during thelast part of each period when the associated right-of-way signal isoperated.

15. In a trafiic signaling system for a trafiic lane having a pluralityof traflic intersections therealong, signals at said intersections forgiving right-of-way, caution and stop indications to traffic proceedingalong said lane, a control unit at each intersection for controlling theen ergization of the signals at the associated intersection, a linecircuit interconnecting said control units a master unit for controllingsaid control units over said line circuit so that said signalsareenergized in accordance with a predetermined signaling cycle, saidcontrol units individually comprising relays having two correspondingoperating positions, the relays included in certain of said controlunits each being operative to one of said two positions to cause theenergization of the associated right-of-way signal and to the other ofsaid two positions to cause the energization of the associated stopsignal, the relays included in others of said units each being operativeto said one position to cause the energization of the associated stopsignal and to saidother position to cause the energization oftheassociated right-of-way signal, means included in said master unitfor controlling said relays over said line circuit to cause said relaysto operate between said two positions in synchronism at least onceduring each" signaling cycle, said control units individually includingadditional relays each operative to cause the energization of theassociated caution signal, means included in said master unit forcontrolling said additional relays over said line circuit to cause eachof said additional relays to operate during the last part of each periodwhen the associated right-of-way signal is operated, and means includedin said master unit for controlling said first-mentioned relays oversaid line circuit to cause each of the first-mentioned relaysrespectively included in said certain control units to occupy one ofsaid two positions and each of the first-mentioned relays respectivelyincluded in said other control units to occupy the other of said twopositions concurrently for a portion of each signaling cycle.

CLARENCE E. LOMAX.

